Hardware placement and maintenance scheduling in high availability systems

ABSTRACT

A method of organizing computer resources includes receiving a specification defining a plurality of quiescence groups of independent component instances for each of at least two services, and performing a first load balancing of the quiescence groups across a plurality of physical servers to define a plurality of supergroups while assigning each of the physical servers across the supergroups.

BACKGROUND

The present disclosure relates generally to the maintenance of acomputer system, and more particularly to methods for organizing andmaintaining resources of the computer system.

Conventional virtual machine (VM) high availability (HA) systems poolVMs and the physical servers they reside on into one or more clusters.The physical servers, or hosts, in the cluster are monitored, and in theevent of a host failure the VMs on a failed host are restarted onalternate hosts.

Two or more VMs providing a given service in the HA system are typicallyanti-collocated on different physical servers to ensure faultcontainment relative to physical server failures, wherein a serviceprovided by the VMs is live or available if at least one VM is running.

A single HA system can support multiple services at same time. Moreover,the HA system may support multiple tenancy, users, roles, etc. Eachservice typically includes of a number of components, such as awebserver, database, etc. The HA system supports multiple instances ofeach component. These components (with at least one instance of eachcomponent) should be live or available so that the service they provideis live or available.

In conventional HA systems, in a case where components need maintenance(e.g., upgrade, patching, etc.), several instances of the components aretaken down, while other instances remain live, without affecting acurrent availability of the service, the taken-down instances aremaintained (e.g., upgraded, patched), and the instances are brought up.This take-down/bring-up process can be repeated with other instances ofthe components.

SUMMARY

According to some embodiments of the present invention, a method oforganizing computer resources includes receiving a specificationdefining a plurality of quiescence groups of independent componentinstances for each of at least two services, and performing a first loadbalancing of the quiescence groups across a plurality of physicalservers to define a plurality of supergroups while assigning each of thephysical servers across the supergroups. In some embodiments of thepresent invention, the method includes performing a maintenance functionon portions of the computer system supporting sequential ones of thesupergroups without interrupting the services, wherein performing themaintenance function includes taking down, simultaneously, theindependent component instances of the quiescence groups within a givensupergroup.

According to some embodiments of the present invention, in a method ofmaintaining resources of a computer system, the computer system beingorganized into a plurality of supergroups, each of the supergroupsincluding at least one quiescence group of independent componentinstances executing on different physical servers, the method includesdetermining a minimum achievable number of supergroups needed to performa service of the computer system, sorting the quiescence groups in aplurality of services by resource consumption, sorting the supergroupsby resource utilization, and selecting each of the quiescence groupssequentially beginning with a quiescence group having a heaviestresource consumption, and placing a currently selected quiescence groupon a supergroup having a lowest resource utilization among thesupergroups and into which the currently selected quiescence group fits,and within the supergroup having the lowest resource utilization placingthe currently selected quiescence group on a physical service having alowest resource utilization among the physical servers, and resortingthe supergroups by resource utilization upon placing the currentlyselected quiescence group. In some embodiments, placing the currentlyselected quiescence group on the supergroup having the lowest resourceutilization among the supergroups and into which the currently selectedquiescence group fits further includes determining that the currentlyselected quiescence group does not fit in any of the supergroups, addinga physical server to one of the supergroups having a highest resourceutilization, and placing the selected group on the physical server addedto the supergroup having the highest resource utilization.

According to some embodiments of the present invention, in a method ofmaintaining resources of a computer system, the computer system beingorganized into a plurality of supergroups, each of the supergroupsincluding at least one quiescence group of independent componentinstances executing on different physical servers, the method includesdetermining a minimum achievable number of supergroups needed to performa service of the computer system, placing the quiescence groups into thesupergroups, wherein at least one of the quiescence groups is placed ineach of the supergroups and each of the quiescence groups comprisesindependent component instances of the service, assigning a plurality ofphysical servers to each of the supergroups, and load-balancing theindependent component instances to the physical servers assigned to eachof the supergroups, wherein the placement of the quiescence groups intothe supergroups is performed without knowledge of the physical servers.In some embodiments, the method further includes adding a new physicalserver to a first supergroup of the supergroups upon determining that aresource of the first supergroup's physical servers is insufficient forthe quiescence groups of the first supergroup.

As used herein, “facilitating” an action includes performing the action,making the action easier, helping to carry the action out, or causingthe action to be performed. Thus, by way of example and not limitation,instructions executing on one processor might facilitate an actioncarried out by instructions executing on a remote processor, by sendingappropriate data or commands to cause or aid the action to be performed.For the avoidance of doubt, where an actor facilitates an action byother than performing the action, the action is nevertheless performedby some entity or combination of entities.

One or more embodiments of the invention or elements thereof can beimplemented in the form of a computer program product including acomputer readable storage medium with computer usable program code forperforming the method steps indicated. Furthermore, one or moreembodiments of the invention or elements thereof can be implemented inthe form of a system (or apparatus) including a memory, and at least oneprocessor that is coupled to the memory and operative to performexemplary method steps. Yet further, in another aspect, one or moreembodiments of the invention or elements thereof can be implemented inthe form of means for carrying out one or more of the method stepsdescribed herein; the means can include (i) hardware module(s), (ii)software module(s) stored in a computer readable storage medium (ormultiple such media) and implemented on a hardware processor, or (iii) acombination of (i) and (ii); any of (i)-(iii) implement the specifictechniques set forth herein.

Techniques of the present invention can provide substantial beneficialtechnical effects. For example, one or more embodiments may provide for:

-   -   a. a combined approach to Quiescence Group placement and upgrade        wave scheduling reducing a maintenance window; and    -   b. reduction of the maintenance window duration improving        hardware utilization and high availability protection.

These and other features and advantages of the present invention willbecome apparent from the following detailed description of illustrativeembodiments thereof, which is to be read in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will be described belowin more detail, with reference to the accompanying drawings:

FIG. 1 is a diagram of a high availability cluster according to anexemplary embodiment of the present invention;

FIG. 2 is a diagram illustrating a method for rolling upgrades accordingto an exemplary embodiment of the present invention;

FIG. 3 shows a service topology according to an exemplary embodiment ofthe present invention;

FIG. 4 shows a service quiescence group according to an exemplaryembodiment of the present invention;

FIG. 5 shows a system comprising a plurality of quiescence supergroupsaccording to an exemplary embodiment of the present invention;

FIG. 6 shows a system comprising a plurality of quiescence supergroupsaccording to an exemplary embodiment of the present invention;

FIG. 7 is a diagram illustrating a method for quiescence supergroupplacement according to an exemplary embodiment of the present invention;

FIG. 8 is a diagram illustrating a method for upgrade wave schedulingaccording to an exemplary embodiment of the present invention; and

FIG. 9 is a block diagram depicting an exemplary computer systemembodying a method according to an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION

Embodiments of the present invention related to the maintenance ofvirtual machine (VM) systems, without interrupting or breaking theservices running on the system such that high availability (HA) isachieved. It should be understood that HA refers to a tolerance of asystem to failures of a (typically predetermined) number of instances ofa component. HA can be defined by compliance or regulatory requirements.

Some embodiments of the present invention improve (e.g., reduce) a totalmaintenance time (e.g., patch time, maintenance window, etc.) for theVM-HA system by taking down certain instances, without interrupting theservice that the instances below to. Further, some embodiments of thepresent invention address a problem of maintaining (e.g., upgrading,patching) host (e.g., physical machine or VM) component instances (VMsor containers) on a same host (e.g., VMs on the same physical machine,or containers on the same VM), which can be constrained by dependenciesof the instances on the physical machine (or VM if the instance is acontainer). It should be understood that embodiments of the presentinvention include heuristic combinations of these technologicalimprovements.

Embodiments of the present invention are applicable to hosts including,for example, physical machines and availability zones.

Some embodiments of the present invention are directed to quiescencegroups (QGs), which capture sets of component instances that can betaken down at the same time. According to one or more embodiments of thepresent invention, if two or more VMs (or containers) can be taken downat a same time without bringing down the service, then these VMs can beplaced in a QG. Embodiments of the present invention include aformulation of the problem of QG placement. Some embodiments of thepresent invention include a method that leverages the input of the QGsto improve a total service time and/or hardware utilization.

According to an embodiment of the present invention, VMs, containers andinstances that are taken down (quiesced, taken offline, etc.) stopexecuting on a processor. An instance that has been taken down is thenavailable for maintenance, wherein for example, the code of the instancestored in persistent memory can be patched or upgraded.

According to one or more embodiments of the present invention, aplurality of QGs capture those VMs/containers that can be quiesced at asame time, while not affecting the any service's availability. Accordingto an exemplary embodiment of the present invention, each QG is apartition of the entire VM/container (component instance) set. Allcomponent instances (resources) of the system are partitioned into theQGs. In some embodiments, the QGs are given or predefined by developersor administrators to reflect dependencies of the VMs/containers in allservices. The QGs can be defined to support QoS (quality of service)goals, constraints, requirements, etc.

In a system comprising a plurality of physical servers and QGs, theplacement of the QGs on the physical servers and the scheduling of thephysical server maintenance affects the time needed for maintenancetask(s). More particularly, the time needed for maintenance can beimpacted by the placement and sequence of maintenance waves orsupergroups. Maintenance waves are configured such that no service isbroken by having more than one QG on a downed physical server in a givenwave. Each maintenance wave corresponds to a round of take-downs of QGs.Moreover, the maintenance waves are configured such that a fewest numberof waves is used for the maintenance task(s), which reduces (e.g.,minimize) an overall maintenance time, while the workload of the QGs isbalanced across the physical servers, for example, based on ageneralized notion of resource utilization (e.g., processor cores,memory resources including disk and random access memories, etc.).

Embodiments of the present invention are directed to methods foraggregating service QGs into quiescence supergroups (QSG) (also referredto a waves) and assigning the QSG in a load balanced manner toavailability zones (AZ), such that any single QSG can fail or bemaintained without impacting the availability of any service provided bythe system.

FIG. 1 illustrates a HA cluster 100 comprising two VMs, VM1 and VM2,placed on physical servers A and B, such that failure of either physicalserver will not cause the HA cluster 100 to fail.

It is possible to maintain the underlying physical servers in an HAcluster without incurring an outage via rolling maintenance. Forexample, referring to FIG. 2 and in the case where a maintenance eventincludes a VM upgrade, given HA cluster 100, a physical server A isdisconnected at 201 and upgraded, while VM2 on physical server B runsthe workload. Physical server A is brought up and re-integrated into theHA cluster at 202. Physical server B is disconnected and upgraded at 203while VM 1 on physical server A runs the workload. Physical server B isre-integrated into the HA cluster at 204. In this example, there is noguarantee of high availability during the upgrade. As used herein,maintenance can include repair, firmware upgrade, hardware upgrade, etc.

FIG. 3 illustrates a service including fifteen VMs. The generalconfiguration of the service shown in FIG. 3 exemplifies a deployment ofa Hadoop distributed file system (hdfs). In this example, HA constrainsrequire that at least ⅘ of the master nodes 301 must be up for theservice to be operational, that ½ of the name nodes 302 must be up forthe service to be operational, and that ⅞ of the data nodes 303 must beup for the service to be operational. It should be understood that otherservices may be different HA constraints.

According to an exemplary embodiment of the present invention, FIG. 4illustrates a service divided into QGs, denoted QG<serviceID>, <QGID>(where ID is an identifier). According to one or more embodiments, anysingle QG can be taken down without impairing the operation of theservice such that high availability is maintained. In this example,“Hadoop File System” service 1 has eight QGs. The QGs are typicallycreated by the service architects based on the HA structure of theirservice. It can be assumed for purposes of the present example that tomaintain high availability at least ⅘ of the master nodes (e.g., VMs) atlevel 401 must be up for service to be operational, that at least ½ ofthe name nodes at level 402 must be up for service to be operational andthat at least ⅞ of the data nodes at level 403 must be up for service tobe operational. With each of the QGs placed on a different physicalserver, any single physical server containing a single QG can fail or beserviced without taking down the service.

Referring now to FIG. 5, according to some embodiments, a QSG is acombination of QGs from one or more services (e.g., QSGs 1-8 contain theQGs from services 1 and 2). As shown in FIG. 5, QSG1 501 includes QG1,1and QGF2,1. In some embodiments, each QSG contains not more than one QGfor any given service. For example, no QSG will contain both QG1,1 andQG1,4. According to an exemplary embodiment of the present invention,one QSG can fail or be taken down for maintenance without disrupting theoperation of any service.

As shown in FIG. 6, the QSGs 600, once created, can be placed onphysical servers, or more generally, into AZs 601-608. Any single AZ601-608 can be shut down without causing an outage of any service. Insome embodiments, an AZ can include a disjoint collection of physicalservers. According to some embodiments, any single AZ 601-608 can failwithout causing an outage of any service.

Referring now to FIG. 7, according to one or more embodiments of thepresent invention, in a method of QSG placement 700, a set of QGs isreceived 702 (for example, defined by one or more service owners). A setof QGs within a service can be written as: QG(i, j), where i==service IDand j==QG ID within service i. The method includes determining a minimumachievable number of supergroups, wherein the minimum achievable numberof supergroups, N, is the largest number of QGs contained by any service(e.g., N==max|QG(i,j)| for all i,j) 702. At block 703, the QGs are loadbalanced across the N supergroups subject to i!=m for all QG(m,*) insupergroup G, wherein m is the set of all services in G (and * is anempty set or placeholder). The load balancing at block 703 includesplacing each QG in a supergroup such that each supergroup includes notmore than one QG from the same service. At block 704, at least onephysical server is assigned to a supergroup. The method further includesload balancing the VMs in each supergroup to the physical servers in thesupergroup 705. At block 705 there is no need to perform an explicitanti-collocation step within a supergroup since anti-collocation isenforced by the supergroup concept.

In some embodiments, portions of a computer system organized accordingto blocks 701-705, can be maintained 706, wherein the maintenancefunction includes taking down, simultaneously, the independent componentinstances of the quiescence groups within a given supergroup.

In view of the foregoing, in the context of the method 700 of FIG. 7,supergroups can be created without knowledge of the hardware they willrun on, which can be useful when deploying to heterogeneous clouds. Itcan be noted that the method 700 may not fully optimize hardwareutilization because no two QSGs can have VMs that coexist on the samephysical server.

Referring to FIG. 8, in a heuristically optimized placement method 800,a set of QGs for a given service are provided 801, which can beexpressed as: QG(i,j), where i==service ID and j==QG ID within thatservice. The method further includes determining a minimum achievablenumber of waves 802. According to at least one embodiment of the presentinvention, upon initiation, all waves start with zero physical servers.In some embodiments the minimum achievable number of waves W is thelargest number of QGs contained by any service, W==max|QG(i,j)| for alli,j. The method further comprises sorting all QGs in all services fromheaviest to lightest 803. According to at least one embodiment, theconcept of a QG's weight is related to resource commitment. Othernotions of weight can be used. At block 804 all waves are sorted byresource utilization, from a wave with the lowest resource utilizationto a wave with the highest resource utilization. It should be understoodthat in some embodiments, a wave's resource utilization is calculated asa sum of the wave's physical servers' resource consumption divided by asum of the wave's physical servers' resource capacities. At blocks805-812, for each QG(i,j), and for each wave w, the method includesattempting to place each QG(i,j) into a wave w with the lowest resourceutilization subject to the constraint i!=m for all QG(m,*) in wave w,and within wave w place QG(i,j) on a physical server having a lowestresource utilization and within which QG(i,j) will fit (see block 807).According to one or more embodiments of the present invention, at block805, the quiescence groups are sequentially selected (through theloop(s) of blocks 805-812) beginning with a quiescence group having aheaviest resource consumption among all the quiescence groups. It shouldbe understood that in some embodiments the physical server resourceutilization is calculated as the physical server resource consumptiondivided by the physical server resource capacity. The load balancing atblocks 805-812 includes placing each QG in a wave such that each waveincludes not more than one QG from the same service. If QG(i,j) is fitin a currently selected wave w at 807-808, go to next QG at 810 and ifQG(i, j) does not fit in any wave 811, a physical server is added to thewave win W having the highest resource utilization 812, for which i!=mfor all QG(m,*) in wave w, and place QG(i,j) into that wave w. At block809, the waves are re-sorted by resource utilization.

It should be understood that the method 800 of FIG. 8 improves hardwareutilization. It can be noted that the method 800 ties the creation ofthe waves or supergroups to a given hardware capability.

In some embodiments, portions of a computer system organized accordingto blocks 801-810, can be maintained 813, wherein the maintenancefunction includes taking down, simultaneously, the independent componentinstances of the quiescence groups within a given supergroup.

In some embodiments, the overall principles of assigning resources tomultiple availability zones is applicable to a number of other domains,such as scheduling maintenance on any complex physical or logicalsystem. Stated another way, while this disclosure is couched in terms ofhighly available clusters composed of Quiescence Groups, it should beclear that the method for eliminating outages due to planned maintenancewould apply to any isomorphic problem, including placement of resourcesacross multiple sites for disaster recovery, and planned maintenance ofthe sites, and placement of storage on array of redundant disk drivegroups that need to be proactively maintained based on failureprediction.

Recapitulation

According to an embodiment of the present invention, a method oforganizing computer resources includes receiving a specificationdefining a plurality of quiescence groups of independent componentinstances for each of at least two services 701, and performing a firstload balancing of the quiescence groups across a plurality of physicalservers to define a plurality of supergroups 703 while assigning each ofthe physical servers across the supergroups 704. In some embodiments,each of the supergroups contains a set of the component instances fromat least one of the services, and the assignment of the physical serversacross the supergroups balances a load thereof 704, and the methodfurther comprises performing a second load balancing of the componentinstances in each of the supergroups to the physical servers thereof705.

According to some embodiments of the present invention, in a method oforganizing resources of a computer system, the computer system beingorganized into a plurality of supergroups, each of the supergroupsincluding at least one quiescence group of independent componentinstances executing on different physical servers, the method includesdetermining a minimum achievable number of supergroups needed to performa service of the computer system 802, sorting the quiescence groups in aplurality of services by resource consumption 803, sorting thesupergroups by resource utilization 804, and selecting each of thequiescence groups sequentially beginning with a quiescence group havinga heaviest resource consumption 805, and placing a currently selectedquiescence group on a supergroup having a lowest resource utilizationamong the supergroups and into which the currently selected quiescencegroup fits 807, and within the supergroup having the lowest resourceutilization placing the currently selected quiescence group on aphysical service having a lowest resource utilization among the physicalservers 807, and resorting the supergroups by resource utilization uponplacing the currently selected quiescence group 809. In someembodiments, placing the currently selected quiescence group on thesupergroup having the lowest resource utilization among the supergroupsand into which the currently selected quiescence group fits furtherincludes determining that the currently selected quiescence group doesnot fit in any of the supergroups 808, adding a physical server to oneof the supergroups having a highest resource utilization, and placingthe selected group on the physical server added to the supergroup havingthe highest resource utilization 812.

According to some embodiments of the present invention, in a method oforganizing resources of a computer system, the computer system beingorganized into a plurality of supergroups, each of the supergroupsincluding at least one quiescence group of independent componentinstances executing on different physical servers, the method includesdetermining a minimum achievable number of supergroups needed to performa service of the computer system 702, placing the quiescence groups intothe supergroups 703, wherein at least one of the quiescence groups isplaced in each of the supergroups and each of the quiescence groupscomprises independent component instances of the service, assigning aplurality of physical servers to each of the supergroups 704; andload-balancing the independent component instances to the physicalservers assigned to each of the supergroups 705, wherein the placementof the quiescence groups into the supergroups is performed withoutknowledge of the physical servers. In some embodiments, the methodsfurther includes adding a new physical server to a first supergroup ofthe supergroups upon determining that a resource of the firstsupergroup's physical servers is insufficient for the quiescence groupsof the first supergroup.

The methodologies of embodiments of the disclosure may be particularlywell-suited for use in an electronic device or alternative system.Accordingly, embodiments of the present invention may take the form ofan entirely hardware embodiment or an embodiment combining software andhardware aspects that may all generally be referred to herein as a“processor,” “circuit,” “module” or “system.”

Furthermore, it should be noted that any of the methods described hereincan include an additional step of providing a computer system fororganizing and servicing resources of the computer system. Further, acomputer program product can include a tangible computer-readablerecordable storage medium with code adapted to be executed to carry outone or more method steps described herein, including the provision ofthe system with the distinct software modules.

One or more embodiments of the invention, or elements thereof, can beimplemented in the form of an apparatus including a memory and at leastone processor that is coupled to the memory and operative to performexemplary method steps. FIG. 9 depicts a computer system that may beuseful in implementing one or more aspects and/or elements of theinvention, also representative of a cloud computing node according to anembodiment of the present invention. Referring now to FIG. 9, cloudcomputing node 10 is only one example of a suitable cloud computing nodeand is not intended to suggest any limitation as to the scope of use orfunctionality of embodiments of the invention described herein.Regardless, cloud computing node 10 is capable of being implementedand/or performing any of the functionality set forth hereinabove.

In cloud computing node 10 there is a computer system/server 12, whichis operational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, handheld or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 may be described in the general context ofcomputer system executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 9, computer system/server 12 in cloud computing node 10is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 12 may include, but are not limitedto, one or more processors or processing units 16, a system memory 28,and a bus 18 that couples various system components including systemmemory 28 to processor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, and external disk drivearrays, RAID systems, tape drives, and data archival storage systems,etc.

Thus, one or more embodiments can make use of software running on ageneral purpose computer or workstation. With reference to FIG. 9, suchan implementation might employ, for example, a processor 16, a memory28, and an input/output interface 22 to a display 24 and externaldevice(s) 14 such as a keyboard, a pointing device, or the like. Theterm “processor” as used herein is intended to include any processingdevice, such as, for example, one that includes a CPU (centralprocessing unit) and/or other forms of processing circuitry. Further,the term “processor” may refer to more than one individual processor.The term “memory” is intended to include memory associated with aprocessor or CPU, such as, for example, RAM (random access memory) 30,ROM (read only memory), a fixed memory device (for example, hard drive34), a removable memory device (for example, diskette), a flash memoryand the like. In addition, the phrase “input/output interface” as usedherein, is intended to contemplate an interface to, for example, one ormore mechanisms for inputting data to the processing unit (for example,mouse), and one or more mechanisms for providing results associated withthe processing unit (for example, printer). The processor 16, memory 28,and input/output interface 22 can be interconnected, for example, viabus 18 as part of a data processing unit 12. Suitable interconnections,for example via bus 18, can also be provided to a network interface 20,such as a network card, which can be provided to interface with acomputer network, and to a media interface, such as a diskette or CD-ROMdrive, which can be provided to interface with suitable media.

Accordingly, computer software including instructions or code forperforming the methodologies of the invention, as described herein, maybe stored in one or more of the associated memory devices (for example,ROM, fixed or removable memory) and, when ready to be utilized, loadedin part or in whole (for example, into RAM) and implemented by a CPU.Such software could include, but is not limited to, firmware, residentsoftware, microcode, and the like.

A data processing system suitable for storing and/or executing programcode will include at least one processor 16 coupled directly orindirectly to memory elements 28 through a system bus 18. The memoryelements can include local memory employed during actual implementationof the program code, bulk storage, and cache memories 32 which providetemporary storage of at least some program code in order to reduce thenumber of times code must be retrieved from bulk storage duringimplementation.

Input/output or I/O devices (including but not limited to keyboards,displays, pointing devices, and the like) can be coupled to the systemeither directly or through intervening I/O controllers.

Network adapters 20 may also be coupled to the system to enable the dataprocessing system to become coupled to other data processing systems orremote printers or storage devices through intervening private or publicnetworks. Modems, cable modem and Ethernet cards are just a few of thecurrently available types of network adapters.

As used herein, including the claims, a “server” includes a physicaldata processing system (for example, system 12 as shown in FIG. 9)running a server program. It will be understood that such a physicalserver may or may not include a display and keyboard.

It should be noted that any of the methods described herein can includean additional step of providing a system comprising distinct softwaremodules embodied on a computer readable storage medium; the modules caninclude, for example, any or all of the appropriate elements depicted inthe block diagrams and/or described herein; by way of example and notlimitation, any one, some or all of the modules/blocks and orsub-modules/sub-blocks described. The method steps can then be carriedout using the distinct software modules and/or sub-modules of thesystem, as described above, executing on one or more hardware processorssuch as 16. Further, a computer program product can include acomputer-readable storage medium with code adapted to be implemented tocarry out one or more method steps described herein, including theprovision of the system with the distinct software modules.

One example of user interface that could be employed in some cases ishypertext markup language (HTML) code served out by a server or thelike, to a browser of a computing device of a user. The HTML is parsedby the browser on the user's computing device to create a graphical userinterface (GUI).

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A method of organizing computer resourcescomprising: receiving a specification defining a plurality of quiescencegroups of independent component instances for each of at least twoservices; and performing a first load balancing of the quiescence groupsacross a plurality of physical servers to define a plurality ofsupergroups aggregating different sets of the quiescence groups whileassigning each of the physical servers across the supergroups as neededto support resource utilization of the quiescence groups.
 2. The methodof claim 1, wherein each of the supergroups contains a set of thecomponent instances from at least one of the services, and theassignment of the physical servers across the supergroups balances aload thereof, the method further comprises: performing a second loadbalancing of the component instances in each of the supergroups to thephysical servers thereof.
 3. The method of claim 1, whereinanti-collocation of dependent ones of the component instances to a sameone of the physical servers results from enforcing the definition of thesupergroups, and wherein no anti-collocation operation is performedwithin the supergroups for respective sets of the component instances.4. The method of claim 1, wherein the definition of the plurality ofsupergroups creates a minimum achievable number of the supergroups. 5.The method of claim 1, wherein the assignment of the physical serverscomprises: determining that a first quiescence group of the quiescencegroups does not fit in one of the supergroups; adding a first physicalserver of the physical servers to a first supergroup having a highestresource utilization among the supergroups upon determining that thefirst quiescence group does not fit in one of the supergroups; andplacing the first quiescence group in the first supergroup, wherein nosupergroup includes more than one of the quiescence groups from a sameone of the services coexisting on a same one of the physical servers. 6.The method of claim 1, further comprising: sorting the supergroups byresource utilization; and performing a maintenance function on thecomputer resources supporting a selected one of the supergroups withoutinterrupting the services, wherein performing the maintenance functionincludes taking down, simultaneously, the independent componentinstances of the quiescence groups within the selected supergroup,wherein the selected supergroup is selected according to the resourceutilization.
 7. The method of claim 6, wherein performing themaintenance function includes taking down, simultaneously, theindependent component instances of the quiescence groups within a givensupergroup.
 8. A method of organizing resources of a computer system,the computer system including a plurality of quiescence groups ofindependent component instances configured to provide a service, themethod comprising: determining a minimum achievable number ofsupergroups needed to perform the service; placing the quiescence groupsinto the supergroups, wherein each of the supergroups includes not morethan one of the quiescence groups from the service, and each of thequiescence groups comprises a set of the independent component instancesthat can be taken down while maintaining an availability of the servicethrough remaining ones of the quiescence groups; assigning a pluralityof physical servers to each of the supergroups; and load-balancing theindependent component instances to the physical servers assigned to eachof the supergroups, wherein the placement of the quiescence groups intothe supergroups is performed without knowledge of the physical servers.9. The method of claim 8, further comprising adding a new physicalserver to a first supergroup of the supergroups upon determining that aresource requirement of at least one of the quiescence groups cannot bemet by resources of any of the supergroups, wherein the addition of thenew physical server in the first supergroup satisfies the resourcerequirement of the at least one of the quiescence groups.
 10. The methodof claim 8, further comprising performing a maintenance function onportions of the computer system supporting sequential ones of thesupergroups without interrupting the services.
 11. The method of claim10, wherein performing the maintenance function includes taking down,simultaneously, the independent component instances of the quiescencegroups within a given supergroup.
 12. The method of claim 8, furthercomprising determining the minimum achievable number of supergroupsneeded to perform the service as a largest number of quiescence groupscontained by any of a plurality of services provided by the computersystem, including the service.